Web registering and tension control system for multi-unit presses



June 20, W. F HUCK ERING AND TENSION CONTROL SYSTEM FOR MULTI-UNIT PRESS 15 Filed Aug .19, 1966 WEB REGIST INVENTOR.

WILLIAM F. HUCK SE28 m A TTORNE Y United States Patent 3,326,436 WEB REGESTERING AND TENSION CONTROL SYSTEM FOR MULTI UNIT PRESSES William F. Huck, 81 Greenway Terrace, Forest Hills, N.Y. 11375 Filed Aug. 19, 1966, Ser. No. 573,679 11 Claims. (Cl. 226-25) This invention relates to web processing machines and more particularly to apparatus for controlling the register and tension of the web in a multi-unit web processing machine, such as, for example, a multi-color rotary gravure printing press. The present application is a continuation-in-part of my copending application for Us. Letters Patent identified as Ser. No. 287,622, filed June 13, 1963 now US. Patent No. 3,280,737.

It is of course important to the proper operation of such multi-unit web processing machines that the printing or other action of each unit take place at locations on the web kept accurately in register with the locations acted upon by every other unit.

Although it is theoretically possible to adjust several processing units so that the operations they perform will be in register, in practice register errors occur as a result of one or more of a variety of variable factors. Variations of the thickness, the moisture content, the temperature or the strength of the paper or other web material being processed tend to produce register errors. So also will variationsof press room atmospheric conditions press operating speeds, Web tension and other conditions aflecting the web on the machine, or the dimensions or constancyof action of the web engaging rotary units of the machine.

It is known that register errors may be corrected by selectively varying the ei fective length of the web between a processing unit where a register error has been detected and the preceding unit. This length variation may be accomplished by displacing or by varying the speed of a roller or a web propelling couple acting upon the web travelling to the farther unit. It will be evident that varying the web length between two processing units in order to correct a register error at the farther unit tends to disturb the register of the Web at the nearer unit and, to a lesser extent, at all preceding units, since the tension effects of web length variation at one location in the machine tend'to pass through the entire machine. This problem is of course aggravated when the correction of a small register error requires a comparatively large'change in the effective web length, as when the correction is effected by varying the rotational speed of the cylinders positively gripping and propelling the web at one printing station of a multi-color rotary printing press relative to the rotational speed of the cylinders at another printing station to vary the tension or stretch of the web in the extended path between the two printing stations or units.

Even when the web travels in an extended path between two successive processing units, for example, as in a multicolor rotary printing press, correct register of the web relative to the farther or second processing unit can be maintained without disturbing the register of the web to the preceding or first unit by providing driven roller means disposed at a point in the web path ahead of, and preferably adjacent to the second unit and non-slippably engaging and propelling the web to the second unit, means to transiently vary the speed at which such driven roller means propel the Web to the second unit upon detection of a deviation of register marks on the web from registering 3,326,436 Patented June 20, 1967 relation to the printing cylinder or other processing element of the second unit, thereby to vary the stretch of the web lead extending from the roller means to the second unit in the sense to correct the register error, and a floating roller which is yieldably biased against the web lead aproaching the driven roller means so that the tension and thereby the stretch of the web lead between the first unit and the driven roller means is normally maintained su stantially constant irrespective of the register correcting action of the latter, The transient variation of the speed at which the web is propelled to the second unit for maintaining correct register thereto is effected most advantageously by simultaneously displacing and varying the rotational speed of the roller means, so that a dual corrective effect is obtained in the web lead extending from the roller means to the second unit, although either displacement or a rotational speed variation will give the transient variation to some extent. In this manner, so long as the web travelling to the second processing unit has register marks thereon, any deviation of such marks from registering relation to the processing element of the second unit is quickly and positively corrected Without objectionable hunting of the register control devices and without disturbing the register of the web to the preceding or first unit.

However, at various times a web lacking the register marks, for example, an unprinted or white web, may be fed to the second processing unit, in which event the devices normally controlling the speed at which the driven roller means propel the web to the second unit cannot function for lack of the register marks on the Web. When this occurs, it may happen that the speed at which the web is propelled by the driven roller means is slightly too high or too low as compared to the speed at which the web is propelled by the printing or other processing units. Such a speed discrepancy will tend progressively to lengthen or shorten the web lead between the preceding or first processing unit and the driven roller means and correspondingly displace the floating roller. The floating roller will soon reach a limit of its range of tension compensating movement and, if the speed discrepancy is allowed to continue, the tension in the web lead extending from the first unit to the driven roller means would thereafter increase so as to break the web, or decrease so as to make such web lead uncontrollably slack.

It is an object of this invention to provide, in a multiunit web processing machine having a system of apparatus which normally quickly and positively corrects detected deviations of register marks on the web from registering relation to a processing unit without disturbing the register of the web to preceding processing units, an arrangement to effectively control the tension of the web travelling to a processing unit when such web is unprinted or otherwise devoid of register marks.

Another object is to provide in such a machine apparatus by which approximately a desired length of the web is obtained in the path between first and second processing units during threading or webbing of the machine preparatory to its normal operation so that, upon commencement of normal operation, the length of the web in such path is approximately equal to a whole multiple of the distance between consecutive register marks applied by the first unit and any error that exists in the register of the marks to the second unit is within a range that can be quickly corrected by the apparatus provided therefor.

A further object is to provide in a multi-unit Web processing machine having register and tension control apparatus of the described character a device by which, following the threading or webbing of the machine, the tension is eased in the web lead extending to the driven roller means from the preceding or first processing unit and any slack is taken up in the web lead extending from the roller means to the second processing unit with which the web is to be maintained in register, whereby to ensure that tension and register control can be accurately exercised upon the commencement of normal operation of the machine.

According to one aspect of the present invention, a multi-unit web processing machine having first and second processing units between which the web travels in an extended path, driven roller means non-slippably engaging the web between the units to propel the web to the second unit, means to vary the speed at which the web is propelled to the second unit by such roller means, for example, to correct for errors in the register relative to the second unit of marks applied to the web by any preceding unit, and a floating roller yieldably biased against and normally counter-balancing the tension of the web upstream of said roller means, such floating roller having a predetermined range of displacement within which it is freely movable in compensation for variations of the web tension without affecting the driven roller means, is further provided with control means rendered operative by displacement of the floating roller to either limit of its range of tension compensating movement to vary the speed at which the web is propelled by the driven roller means in the sense to restore the floating roller to within its range of tension compensating movement, whereby excessive tension or a slack condition is prevented in the web lead between the driven roller means and the preceding unit when the machine is operated without register marks on the web.

In advantageous embodiments of the invention, the structure supporting the floating roller for tension compensating movement has connected thereto a member movable in correspondence with displacements of the floating roller between two limit switches which are selectively tripped or actuated upon displacement of the roller to one or the other of the limits of the range of its tension compensating movement, and such limit switches control the operation of an electrical motor by which a variable speed drive is adjusted to vary the speed at which the web is propelled by the driven roller means in the sense to restore the floating roller to within its range of tension compensating movement.

According to another aspect of the invention, the floating roller is disposed at a predetermined position during threading or webbing of the machine so that the length of the web in the path between successive processing units will be approximately a whole multiple of the distance between consecutive register marks applied to the web, thereby to facilitate the quick attainment of the desired register condition when normal operation of the machine is commenced. Such position to which the floating roller is displaced during threading or webbing of the machine preferably corresponds to the limit of the range of tension compensating movement of the floating roller at which the speed of propulsion of the web by the roller means is decreased so that, when the floating roller is freed to act yieldably against the web during initial operation of the machine, the tension is eased in the web lead extending to the driven roller means from the preceding unit and the slack normally incurred during threading of the machine in the web lead extending from the roller means to the farther unit is taken-up for ensuring proper control of the web during normal operation.

The above mentioned, and other objects, features and advantages of the invention will be further apparent from the following detailed description of illustrative embodiments thereof which is to be read in connection with the accompanying drawing, wherein:

FIG. 1 is a schematic side elevational view of a portion of a multi-unit web processing machine having a web registering and tension control system in accordance with an embodiment of the invention; and

FIG. 2 is a schematic side elevational view of a portion of a tension control apparatus which may be substituted for a corresponding portion of the system of FIG. 1 in accordance with another embodiment of the invention.

In the multi-unit web processing machine shown, in part, on FIG. 1, a web W unwound from a rollstand (not shown) is moved successively through processing units P1 and P2 which may be in the form of rotary gravure printing units each comprising a diagrammatically represented ink fountain system 10 contacting and applying ink to an engraved gravure cylinder 11 against which the web is tightly pressed by a rubber covered or equivalent nip roller 12 under force provided by a steel backup cylinder 13.

The printing units P1 and P2 may repetitively print respective patterns on the web in different colors. Further, the printing unit Pl may apply register marks to the Web at predetermined locations with respect to the patterns printed on the web by that unit and which are to be maintained continually in register with gravure cylinder 11 of the next printing unit P2 so that the patterns printed by the several printing units are in register with each other on the web.

A main press drive shaft 14 rotated by a suitable motor 15 drives the gravure cylinder 11 of each printing unit, for example, through bevel gearing 16, and also drives the rollstand so that the speed at which the web is unwound and the speeds at which the web is propelled by reason of its non-slipping engagement by the gravure cylinders of the several printing units are all equal.

After leaving each printing unit, for example, the printing unit Pl, the web is guided through a drying oven 0 by a plurality of guide rollers 17. From the oven 0, the web is guided to free running cooling cylinders 18 around which the web is trained in serpentine fashion. From the cylinders 18, the web travels over guide rollers 19 and 20, under a guide roller 21, over a floating roller 22 which forms part of a tension control device 23, thence in serpentine fashion around drive rollers 24 and 25 which form part of a register control device 26, and then under a guide roller 27 to the printing unit P2. In web processing machines having more than two printing or other processing units acting successively on the web, a similarly constituted path of travel may be provided between all of the successive printing units. Further, where the web unwound from the rollstand is preprinted or otherwise provided with register marks, the web travelling from the rollstand to the first printing unit Pl may be also acted upon by a tension control device and a register control device similar to the devices 23 and 26, respectively, which are hereinafter described in detail.

The register control device 26, as shown, includes a displaceable carriage 28 rotatably supporting drive rollers 24 and 25. A V-belt pulley 29 is secured to an extension of drive roller 25 and is driven by a V-belt 30 trained around a V-belt pulley 31 mounted on a fixed axis. The pulley 31 is driven from the main press drive shaft 14, for example, through bevel gearing 32, a take-off shaft 33 and bevel gearing 34. Drive roller 24 is driven from roller 25 by suitable gear means (not shown), so that, when motor 15 is active, drive rollers 24 and 25 are driven in opposite directions and in synch-ronism with the units P1 and P2 and cooperate with these units to propel the web along the extended path between the web processing units.

The carriage 28 has a mounting arm 35 securing it for pivotal reciprocating movement on a shaft 36 which is journalled in the press frame. An arm 37 is secured at one end to the shaft 36 and at its other end carries a pivotally mounted nut 38 which is engaged by a screw 39 coupled to the output shaft of a reversible electric motor 40 so that upon actuation of motor 40 the carriage 28 is pivoted about the axis of shaft 36 to move drive rollers 24 and 25 toward or away from printing unit P2.

Pivotally mounted on carriage 28 are arms 41 carrying pressure rollers 42 at their outer ends. Spring means (not shown) are operative to hold the rollers 42 and thereby web W in non-slip driving contact with drive rollers 24 and 25, so that movement of rollers 2 and toward or away from unit P2 moves the web portion engaged by these rollers toward or away from this unit.

It will be evident that such displacement of drive rollers 24 and 25 has the effect of transiently varying the speed of movement of the portion of the web engaged by these rollers, relative to the speed of the portion of the web engaged by unit P-2, and thus will vary the stretch of the web lead extending from rollers 24 and 25 to unit P-2.

The belt-contacting radius of the V-belt pulley 31 is variable in response to variations of the tension of V- belt 30. The pulley 31 may be, for example, of the type disclosed in my United States Patent No. 2,812,666. Tensioning rollers 43 carried on the free ends of arms 44 clamped to stub shafts -45 bear against V-belt and are adjustable by adjustment of arms 44 on shaft to vary the belt contacting radius of pulley 31 so as to establish the desired initial ratio of the peripheral speed of rollers 24 and 25 to the peripheral speed of the cylinders in unit P2.

It will be seen that the aforedescribed displacement of drive rollers 24 and 25 toward or away from the unit P-2 in response to actuation of the motor 40 will vary the tension of belt 30 and thereby vary the belt contacting radius of pulley 31 and the speed of the belt 30, whereby to vary the rotational speed of rollers 24 and 25 relative to that of the printing unit. Specifically, movement of rollers 24 and 25 toward unit P-2 increases the rotational speed of rollers 24 and 25, and movement of rollers 24 and 25 away from unit P-2 decreases their rotational speed. Thus, as these rollers are moved closer to the printing unit their peripheral speed and the speed of the web portion propelled by them is increased relative to the speed of the web portion engaged by unit P-2, while the opposite effect is obtained when rollers 24 and 25 are moved farther away from the printing unit. That is, the elfects of the bodily movement and the simultaneous speed variation of rollers 24 and 25 are additive, so that there is a dual effect upon the stretch of the web lead extending from these rollers to unit P-2.

A photoelectric scanning head is disposed adjacent the variably stretched web lead between drive rollers 24 and 25 and the proximate printing unit, and may be of the type commercially available from the Specialty Control Department of The General Electric Company, Waynesboro, Va., as Item No. CR7515P202G4. A scanning head of the identified type includes a light source directing a beam of light against the web and a photoelectric cell which measures the intensity of the light of the beam that is reflected by the web toward the cell.

The scanning head 46 emits an electrical signal each time a register element, such as, for example, a register mark applied to the web W by printing unit P-l, passes a fixed point in the area scanned by the head. The signals from head 46 are compared with a series of electrical signals emanating from a photoelectric selector switch 47 which is driven from gravure cylinder 11 of unit P-2 through'a non-slip belt and pulley transmission 48. The switch 47 may be of the type commercially available from the Specialty Control Department of The General Electric Company, Waynesboro, Va., as 'Item No. CR7515-P145G4.

The signals from head 46 and those from switch 4-7 are fed to and compared by a control panel 49, which may be of the type commercially available from the Specialty Control Department of The General Electric Company, Waynesboro, Va., as Item No. 357515-CT100-Al. The control panel 49 is operative to generate an error signal in response to the detection of a lack of synchronisation between the signals from head 46 and those from switch 47, andthese error signals, which are proportional in magnitude to the register error detected, are fed to the reversible motor 40 to cause rotation of that motor in the direction and to the extent required to correct the detected error.

Specifically, if the signals from head 46 lag behind those from switch 47, indicating that the register marks on the web W are lagging behind the required register position with respect to gravure cylinder 11 of unit P2, motor 40 is rotated in the direction to pivot carriage 28 clockwise (as viewed on FIG. 1) about the axis of shaft 36. Such pivotalmovement of carriage 28 moves rollers 24 and 25 toward unit P-2 to displace the web portion engaged by them toward that unit and simultaneously increases the rotational speed of rollers 24 and 25. Both of these actions, increase the speed of the web portion propelled by the drive rollers relative to the speed at which the web is propelled by unit 'P-2. As a result, the stretch of the relatively short we'b lead between rollers 24 and 25 and gravure cylinder 11 of unit P-i-2 will be reduced to move the register marks on the web directly to their position of correct register with the gravure cylinder.

If the signals from head 46 are ahead of those from switch 47, indicating that the register marks on web W are ahead of the required register position with respect to gravure cylinder 11 of unit P-2, motor 40 is rotated in the direction to pivot carriage 28 counterclockwise, thus displacing rollers 24 and 25 and the web portion engaged by them farther away from the cylinder and simultaneously and proportionally decreasing the rotational speed of rollers 24 and 25 so as to increase the stretch in the web lead between such rollers and cylinder 11 of unit P-2.

Any displacement or rotational speed variation of rollers 24 and 25 of course tends also to vary the tension and thereby the stretch of the relatively long web lead extending from the preceeding printing unit P4 to these rollers. Such a variation is prevented, however, by the floating roller 22 of the tension control device 23 over which the web lead from unit P-1 passes as it approaches the drive rollers 24 and 25.

As shown 011 FIG. 1, the tension control device 23 includes an arm 50, which may be one of a pair of arms, each pivotally mounted between its ends on a shaft 51 and rotata'bly carrying the floating roller 22 at one of its ends. The other end of arm 50 is secured to the piston of a fluid pressure cylinder 52 pivotally suspended from the frame of the press. A conduit 53 extends to cylinder 52 from a source (not shown) of compressed air or other fluid under pressure, and a pressure regulator valve 54 is interposed in conduit 53 to adjust the fluid pressure acting against the piston in cylinder 52. The magnitude of such adjusted fluid pressure is indicated by a pressure gauge 55 which is connected to conduit 53 and may be calibrated in units of web tension to provide a continuous and easily readable indication of web tension.

The web W wraps around roller 22 in a direction such that the pull of the tensioned web on this roller urges the roller downwardly with a force that is resisted bv the pressure of the air acting on the riston in cylinder 52, so that the magnitude of the tension in the web lead between unit P-1 and drive rollers 24 and 25 is determined by the magnitude of the air pressure supplied to cylinder 52 and is normally maintained at that value irrespective of the Web and roller displacements caused by bodily movements and variations in the rotational speed of rollers 24 and 25.

The tension control device 23 and the register control device 26 thus normally act in conjunction to vary the tension and thereby the stretch of the relatively short lead of the web between rollers 24 and 25 and unit P-2 in the sense and to the extent required for quick correction of detected errors in register of the successive printed patterns or other processed locations on the web with re- Z spect to gravure cylinder 11 of unit P-2, while maintaining substantially constant the tension and thereby the stretch of the relatively long lead of the web between unit P-1 and register control device 26 so as not to disturb the register of the web to unit P-l.

It may be desired at various times to feed an unprinted or white web to printing unit P2 from unit P1, or directly from the rollstand, in which event register control device 26 cannot 'function in the normal manner described above for lack of register marks on the web. When this occurs, it may happen that carriage 28 of device 26 is so positioned that the rotational speed imparted to rollers 24 and by the belt contacting radius of variable diameter pulley 31 is slightly too high or too low as compared to the speed of the printing units. Such a speed discrepancy will tend progressively to lengthen or shorten the web lead between unit P-1 and rollers 24 and 25 and correspondingly to displace floating roller 22. That roller 22, however, will soon reach a limit of its range of tension compensating movement and, if the speed discrepancy is allowed to continue, the web tension will thereafter increase so as to break the web, or decrease so as to make the web lead uncontrollably slack.

In order to prevent any such difliculty, further means are provided according to this invention for automatically dis-placing carriage 28 in the direction and to the extent required for eliminating the speed discrepancy, whenever the floating roller 22 reaches either limit of its normal range of tension compensating movement. These means, as seen on FIG. 1, include an arm 56 secured in depending position to the shaft 51 which carries the arms supporting floating roller 22, and being arranged so that, as floating roller 22 approaches either limit of its range of tension compensating movement, arm 56 actuates one or the other of a pair of limit switches 57 and 58 disposed at opposite sides of actuating arm 56. The switches 57 and 58 are electrically connected to the control panel 49 by circuits 59 and 60, respectively. The circuitry is such that, when either of the switches 57 and 58 is actuated, the motor 40 is energized through the control panel 49 in a sense to move the carriage 28 in the direction to prevent the impending harmful increase or decrease of the tension in the web lead extending from unit P1 to rollers 24 and 25. A cut-off switch 61 may be provided in the circuits 59 and to incapacitate switches 57 and 58 when printed paper is being supplied to the unit P-2 and thus has register marks to be scanned by the head 46 in the normal operation of register control device 26.

It is desirable under certain conditions that the energization of motor 40 and displacement of carriage 28 in response to actuation of either of the switches 57 and 58 be made cyclical or intermittent. This may be accomplished by the phasing device indicated generally at 62 on FIG. 1. The device 62 includes a gear reduction unit 63 supported in a position adjacent to one of the printing units, for example, the printing unit P-l, as shown, and having its input shaft driven from the latter by a belt and pulley transmission 64. Secured to the relatively slowly turning output shaft of the unit 63 is a cam 65 which cyclically actuates a switch 66 interposed in the electrical circuits 59 and 60 so that the motor 40 is energized only when one of the limit switches 57 and 58 is actuated by the arm 56 and the switch 66 is actuated by the cam 65. A cut-off switch 67 may also be provided to electrically by-pass the switch 66 when continuous rather than intermittent energization of motor 40 is desired.

Referring now to FIG. 2, it will be seen that the tension control device 23a there illustrated, and which may be substituted for the previously described device 23, has its floating roller 22a rotatably carried, at its ends, by support arms 69 which extend from, and are secured to a shaft 70 journalled in the press frame. At least one of the arms 69 has its free end portion pivotally connected, as at 71, to the piston rod or ram 72 of the fluid pressure cylinder 52a which is supported by the press frame, as at 74. Compressed air or other fluid under pressure is supplied to the lower end of cylinder 52a by way of conduit 53a from a source (not shown), and the pressure of the fluid supplied to cylinder 52a is suitably controlled, as in the previously described embodiment of this invention.

As in the device 23, the web W wraps around roller 22a in a direction such that the pull of the tensioned web on roller 23a urges the latter downwardly with a force that is yieldably resisted by the pressure of fluid acting in cy-linder 52a, so that the magnitude of the tension in the web lead extending from unit P1 to drive rollers 24- and 25 is determined by the magnitude of the fluid pressure supplied through conduit 53a and is normally maintained at that value irrespective of the web displacements caused by variations in the rotational speed of drive rollers 24 and 25.

One of arms 69 has an extension 75 for selectively ctuating one or the other of the two spaced apart limit switches 57a and 58a when roller 22a is displaced to either limit of its ran e of tension compensating movement. The switches 57a and 58a are preferably mounted for adjustment relative to each other and for adjustment as a unit so as to vary the positions of roller 22a at which switches 57a and 58a are selectively actuated. For example, the switches 57a and 58a may be individually adjustable along a longitudinally slotted support 76 which is, in turn, slidably adjustable along a fixedly mounted bracket 77, as by turning of an adjusting screw 78. Limit switches'57a and 58a may be connected to the control panel 49 of FIG. 1 through electrical circuits similar to those previously described with respect to the limit switches 57 and 58. Thus, when the peripheral speed of rollers 24 and 25 is too low in relation to the speed at which the web is propelled by unit P4. so that roller 22a is displaced upwardly to the limit of its range of tension compensating movement at which switch 58a is actuated, motor 40 is operated either intermittently or continuously in the direction for increasing the speed at which the web W is propelled by drive rollers 24 and 25, thereby returning roller 22a to within its range of tension compensating movement for preventing an uncontrollably slack condition in the web lead extending from unit P1 to the drive rollers of register control device 26. Conversely, when roller 22a is displaced downwardly to the limit of its range of tension compensating movement at which switch 57a is actuated, motor 40 is operated in the direction for decreasing the speed at which the web is propelled by drive rollers 24 and 25, thereby to return roller 22a to within its range of tension compensating movement and prevent a harmfully high tension in the web lead extending from unit P-ll to the register control device 26 that could cause tearing of the web.

In order to dispose floating roller 22a at a predetermined position at which approximately the desired length along the Web in the path between successive units P-1 and P-2 is obtained during initial webbing of the press, the tension control device 23a is further provided with a fluid pressure cylinder 79 mounted, as at 80, on the press frame and having a piston rod or ram 81 projecting upwardly therefrom. A roller 82 is mounted at the upper end of piston rod 81 and is normally spaced well above the free end portion of an arm 83 extending from shaft 70.

During webbing of the press, compressed air or other fluid under suitably controlled pressure is supplied to the upper end of cylinder 39 through a conduit 84 so that piston rod 81 is retracted and moves the roller 82 carried thereby downwardly against arm 83. The force exerted by the compressed air acting in cylinder 79 and tending to cause downward movement of floating roller 22a is sufliciently high to overcome the contrary force of the compressed air acting in cylinder 520. Thus, arm 83 is displaced downwardly and, through shaft 70, causes downward displacement of arms 69 and floating roller 22a.

The downward displacement of roller 22a in response to the suplying of compressed air to cylinder 79 is limited by the engagement of a stop collar 85 adjustably secured on piston rod 81 against the upper end of cylinder 79. Switch 57a is preferably disposed so as to be actuated by extension 75 when roller 22a is displaced downwardly to the limit of such movement permitted by stop collar 85. A pointer 86 may be secured on shaft 70 to cooperate with a fixed scale 87 in continually indicating the position of floating roller 22a.

With roller 22a displaced downwardly to the position Where switch 57a is tripped or actuated in response to the supplying of compressed air to cylinder 79, web W is fed from unit P-l, through drying oven and around cooling cylinders 18, over floating roller 22 by way of guide rollers 19, 20 and 21, and then around drive rollers 24 and 25. Pressure or nip rollers 42 are then engaged to provide positive drive of the web by rollers 24 and 25, whereupon the Web is led further under guide roller 27 and through unit P-2. The position of stop collar 85 on piston rod 81 is selected so that, when collar 85 engages the upper end of cylinder 79, roller 22a is disposed to provide a length along the threaded web in the path between units P-1 and P-2 that is approximately a whole multiple of the distance between consecutive register marks to be applied to the web. After threading or webbing of the press has been completed, the supplying of compressed air to cylinder 79 is halted to permit the return of piston rod 31 to its normal extended position, for example, by a spring (not shown) in cylinder 79, whereby roller 82 is elevated to release arm 83. However, the web which engages roller 22a holds the latter in its downwardly displaced position where extension 71 trips switch 57a. Thus, motor 40 is operated in the direction to decrease the speed at which the web is propelled by drive rollers 24 and 25, thereby easing the tension in the web lead extending from unit P-l to drive rollers 24 and 25 and simultaneously taking-up the slack that is normally incurred in the web lead extending from drive rollers 24 and 25 to unit P-2 as a result of the webbing or threading of the press. Since the device 23a ensures that, upon threading or webbing of the machine, the length along the web in the path between units P-1 and P-2 is approximately a whole multiple of the distance between consecutive register marks applied either by unit P1 or earlier to the web, it is possible for the register control device 26 to rapidly establish the correct register condition with respect to unit P-2 when normal operation of the machine commences with register marks applied to the web. Further, the described operation of easing the tension in the web lead be tween unit P-1 and rollers 24 and 25 and of taking up the slack in the web lead between rollers 24 and 25 and unit P2 when operation of the web processing machine commences after threading thereof ensures that the operation of register control device 25 in response to the detection of a register error will be effective immediately to vary the stretch in the web lead between rollers 24 and 25 and unit P-2 for establishing correct register of the web relative to unit P-2 and that the roller 22a will be within the range of its tension compensating movement to prevent disturbance of the register of the web to the preceding unit or units by reason of such operation of device 26.

Although the tension control device 23 and 23a have been shown and described in association with a particular register control device 26, other forms of register control devices may be employed, for example, as disclosed in my previously mentioned application for US. Letters Patent Ser. No. 287,622.

From the foregoing it will be seen that the present invention provides a system of apparatus for a multi-unit web processing machine which acts quickly and positively to correct detected errors in the register of the web to each processing unit during normal operation of the machine on a web having register marks thereon, and without disturbing the register of the web to other processing units; and which prevents harmful variations in the web tension when the web travelling through the machine is imprinted or otherwise without register marks.

Further, it will be seen that a system provided in accordance with the invention may establish conditions during threading or Webbing of the machine and the commencement of its operation which ensure the rapid attainment of correct register of the web to each processing unit, thereby to minimize the waste of paper or other web material.

While illustrative embodiment of the invention have been described in detail herein with reference to the drawing, it will be understood that the new features of the invention can be utilized in many other ways and are not restricted to those illustrative embodiments except as may be required by a fair construction of the appended claims.

What is claimed is:

1. In a web processing machine including a rotary unit for processing a web traveling continuously thereto through an extended path,

driven roller means non-slippably engaging and propelling the web to said unit,

means including a variable speed drive driven in synchronism with said unit for driving said roller means,

a floating idler roller yieldably biased against and normally counterbalancing the tension of the web up stream of said roller means,

said floating roller having a predetermined range of displacement within which it is freely movable without affecting said driven roller means in compensation for variations of said tension,

and means rendered operative by displacement of said floating roller to either limit of said range to actuate said variable speed drive and cause it to vary the speed of the propulsion of the web by said roller means so as to restore said floating roller to tension compensating movement within said range.

2. A web processing machine according to claim 1; wherein the web traveling to said unit normally has successive register marks thereon which are to be maintained continuously in register with a processing element of said unit, and

further comprising register correction means including means for detecting a deviation of said register marks from registering relation to said processing element and means normally responsive to said detecting means for actuating said variable speed drive to cause it to vary the speed at which the Web is propelled by said roller means in the sense required to correct such deviation.

3. A web processing machine according to claim 2; further comprising means operable to dispose said floating roller in a predetermined position during threading of the web through said machine, said position being selected so that the length of the web in said extended path is approximately a whole multiple of the distance between the consecutive register marks which are to be maintained in registering relation to said processing element.

4. A web processing machine according to claim 1; further comprising means operable during threading of the web through the machine to displace said floating roller to,

a position at the limit of said range of its tension compensating movement which corresponds to an increased ten-' sion of the web upstream of said roller means so that, upon commencement of the operation of the machine,

said variable speed drive is actuated to decrease the speed at which the web is propelled by said roller means, thereby to ease the tension in the web upstream of said roller means and to take up any slack in the web lead between said roller means and said unit.

5. A web processing machine according to claim 1; wherein the web traveling to said unit normally has successive register marks thereon which are to be maintained 1 l continuously in register with a processing element of said unit; and

further comprising register correction means including means for detecting a deviation of said register marks from registering relation to said processing element during normal operation of the machine and means normally responsive to said detecting means for actuating said variable speed drive to cause it to vary the speed at which the web is propelled by said roller means in the sense required to correct such deviation, and means operable during threading of the web through the machine to displace said floating roller to a predetermined position at which the length of the web in said extended path is approximately a whole multiple of the distance between consecutive register marks which are to be maintained in registering relation to said processing element, said position of the floating roller being at the limit of its range of tension compensating movement which corresponds to an increased tension of the web upstream of said roller means so that, upon commencement of normal operation of the machine, said variable speed drive is actuated to decrease the speed at which the web is propelled by said roller means, thereby to ease the tension in the web upstream of said roller means and to take-up any slack in the web lead between said roller means and said unit for facilitating the rapid attainment of the registering relation of the register marks to said processing element by said register correction means.

6. A web processing machine according to claim 1; wherein said variable speed drive has a reversible electric motor operable to vary the speed at which said roller means propels the web, and said means to actuate the variable speed drive includes first and second limit switches, circuit means having said switches electrically interposed therein to operate said motor in the directions for increasing and decreasing the speed at which the web is propelled by said roller means in response to tripping of said first and second switches, respectively, a switch actuating member movable with said floating roller and means mounting said first and second switches for tripping by said actuating member upon movement of said floating roller to the opposite limits, respectively, of said range of tension compensating movement which correspond to decreasing and increasing tension in the web upstream of said roller means.

7. A web processing machine according to claim 6; wherein said floating roller is yieldably biased against the web upstream of said roller means by first fluid pressure operated means, and second fluid pressure operated means are provided to overcome the force exerted by said first fluid pressure operated means during threading of the web through the machine and thereby to displace said floating roller to said limit of its range of tension compensating movement which corresponds to increasing web tension 50 that, following the threading of the web through the machine, said second limit switch is tripped to cause said variable speed drive to decrease the speed at which the web is propelled by said roller means for easing the tension in the web upstream of said roller means and taking up any slack in the web lead between said roller 1 means and said unit.

8. A web processing machine according to claim 7; wherein the web traveling to said unit normally has successive register marks thereon which are to be maintained continuously in register with a processing element of said unit, and

further comprising register correction means including means for detecting a deviation of said register marks from regstering relation to said processing element and means responsive to said detecting means for operating said motor of the variable speed drive in the sense for causing the latter to vary the speed at which the web is propelled by said roller means so as to correct such deviation, and adjustable stop means to limit the displacement of said floating roller by said second fluid pressure operated means to a position at which the length along the Web in said extended path is approximately a whole multiple of the distance between the consecutive register marks to be registered with said processing element so that, following the threading of the machine, said register correction means can rapidly attain the registering relation of the register marks to said processing element.

9. In a multi-unit web processing machine including a first set of coacting cylinders which impress a web at successive locations thereon and from which the web travels under tension through an extended path to a second set of coacting cylinders which impress the web at successive locations to be maintained continually in register with the first said locations;

register control means including driven roller means non-slippably engaging and propelling the web at a location between said sets of cylinders for simultaneously and proportionally adjusting relative to the position and the speed of said second set of cylinders both the length of the path and the speed of that lead of the web which extends from said driven roller means to said second set so as to keep the impressions of the web substantially constantly in register irrespective of the actual speed of said cylinder sets, said register control means further including means for driving said cylinder sets and said roller means in synchronism, and a variable speed drive for varying the speed of said roller means relative to the speed of said second cylinder set,

register correction means including means for detecting a deviation of the first said locations from registering relationship to said second set and means responsve to said detecting means for actuating said register control means to the extent and in the sense to correct such deviation,

floating idler roller means yieldably biased against and normally counterbalancing the tension of the web in the lead thereof between said first set of cylinders and said driven roller means, said floating roller means having a predetermined range of displacement within which it is freely movable to maintain a substantially constant tension in the last mentioned Web lead irrespective of variations in the speed of said driven roller means relative to the speed of said first set of cylinders,

and means rendered operative by displacement of said floating roller means to either limit of said range to actuate said variable speed drive and cause it to vary the speed of the propulsion of the web by said driven roller means in the sense to restore said floating roller means to constant tension maintaining movement within said range.

10. A multi-unit web processing machine according to claim 9; further comprising means operable during threading of the web through the machine to dispose said floating roller means in a predetermined position at which the length of the web in said extended path between said first and second sets of cylinders is approximately a whole multiple of the distance between said first successive locations so that, upon operation of the machine following threading of the web therethrough, said register control means can rapidly bring said first locations into registering relationship to said second set of cylinders.

ill. A multi-unit web processing machine according to claim 10; wherein said position to which the floating roller means is displaced durng threading of the web through the machine is at the limit of said range at which said variable speed drive is actuated to cause it to decrease the speed of propulsion of the web by said driven roller means so that, upon said operation of the machine following threading, the tension is eased in said web lead 13 14 between said first set of cylinders and said driven roller 2,723,620 11/1955 Huck 226-25 X means and any slack is taken-up in said web lead between 2,949,295 8/ 1960 Huck 226-40 said driven roller means and said second set of cylinders. 3,087,663 4/ 1963 Anderson 22644 References Cited 3,097,844 7/1963 Huck 22644 UNITED STATES PATENTS 5 M. HENSON WOOD, JR., Primaly Examiner. 2,142,501 1/1939 Dultgen et a1 226-25 X 2,707,254 4/ 1955 Newman et a1 226-30 X A. N. KNOWLES, Assistant Examiner. 

1. IN A WEB PROCESSING MACHINE INCLUDING A ROTARY UNIT FOR PROCESSING A WEB TRAVELING CONTINUOUSLY THERETO THROUGH AN EXTENDED PATH, DRIVEN ROLLER MEANS NON-SLIPPABLY ENGAGING AND PROPELLING THE WEB TO SAID UNIT, MEANS INCLUDING A VARIBLE SPEED DRIVE DRIVEN IN SYNCHRONISM WITH SAID UNIT FOR DRIVING SAID ROLLER MEANS, A FLOATING IDLER ROLLER YIELDABLY BIASED AGAINST AND NORMALLY COUNTERBALANCING THE TENSION OF THE WEB UPSTREAM OF SAID ROLLER MEANS, SAID FLOATING ROLLER HAVING A PREDETERMINED RANGE OF DISPLACEMENT WITHIN WHICH IT IS FREELY MOVABLE WITHOUT AFFECTING SAID DRIVEN ROLLER MEANS IN COMPENSATION FOR VARIATIONS OF SAID TENSION, 